I still say that alarm clock would work. Really though, the most effective alarm sound would be a recording of your spouse saying, “The alarm didn’t go off!” That wakes you up fast.

I once had a cat creep up to me while I was napping, stick her little nose in my ear, and sneeze. I’ve never gone from fast asleep to wide awake so quickly in my life. Cats trained to do this could be used instead of smelling salts to wake up people who have passed out. If someone I love is ever in a coma, I am going to try sneezing in their ear to wake them.